It was a case of good news and bad news for the Scottish National party today as it emerged that North Sea oil revenues would easily fund an independent Scotland - but only for the next 10 years.

With the polls suggesting that the SNP is on course to become the biggest party in the devolved Scottish parliament after the May 3 elections, the ramifications of the party's call for full independence from the rest of the UK are starting to be taken a little bit more seriously.

But the SNP's plans for a £90bn oil fund to improve Scotland's lot in the future seem wide of the mark. If Scotland relied on "black gold" revenue, it would be economically viable - but this would only be enough to cover public expenditure currently funded by the Treasury. Oil prices are also volatile and can be hard to forecast in the long term.

Either way, within 10 years, an independent Scotland would have to find other ways to make ends meet as oil production is expected to drop significantly over the coming decade. A point the Labour party, keen to keep control of the Scottish parliament, has already made.

The FT analysis seems to conclude that the SNP's plan isn't wrong, it just fails to plan for the long term. In the end, without the North Sea cash cow, Scotland would struggle to fund its generous welfare model.

So what would an independent Scotland do next? You can't cut the ties and then come home with your political tail between your legs. Or can you?